1. Field of the Invention
The present invention relates to a lift device for an active hood system, and particularly to a lift device of an active hood system for lifting up a hood in a mechanical system, which employs a suppressed elastic force so as to greatly reduce the impact and injury to the pedestrian during collision
2. Description of Related Art
In general, a passenger vehicle is provided with an engine compartment that is enclosed with a hood. The engine compartment includes components, such as an engine and the like, which are compactly placed therein. The hood protects the parts arranged in the engine compartment from the exterior. To this end, the hood is fixed to the top surface of the engine compartment by means of an upwardly pivotable (or rotatable) hinge.
Such a vehicle could collide with a pedestrian. If so, the pedestrian would first strike the front bumper of the vehicle, then, the pedestrian would bump one's head against the hood while falling toward the upper surface of hood. Due to this, the impact derived from the series of impacts may result in serious injury to the pedestrian.
Recently, pedestrian protection regulations are being enforced due to the aforementioned dangers. To meet the pedestrian protection regulations, an active hood system was proposed that is able to provide a space between the hood and the engine compartment, and sufficiently absorb the impact energy applied to a pedestrian at the time of collision with the vehicle.
For example, there is an active hood system disclosed in the Korean Publication No. 2006-0067219 (“the '219 publication”), as shown in FIG. 1. Referring to FIG. 1, the active hood system of the '219 publication includes an actuator 10, which is installed between the hood and the engine compartment. The actuator 10 lifts up the hood so as to minimize the impact applied to the pedestrian during a collision.
To this end, the actuator 10 is configured in the same structure as an antenna, which extends and shortens in multiple telescopic steps. Also, an elastic member 11 is provided in the actuator 10 having the same structure as the antenna. Furthermore, a locking member 20 is installed in a specific region of the bottom of the actuator 10 and holds the actuator 10 from being extended from a minimally shortened state.
Such an active hood system of the '219 publication allows the elastic member 11 to resiliently lift up the hood and provide the buffer space. Accordingly, the active hood system of the '219 publication can protect the pedestrian by means of the buffer space.
However, in the active hood system of the '219 publication, a connection portion between a panel and an extending rod can be moved and a joint between them can be generated. Moreover, the active hood system of the '219 publication requires a large capacity of solenoid actuator, enough to perform an unlocking operation in which a large fractional force is generated.
As another example, an active hood system with a latch actuator is described in the International Patent Publication No. 2004/000975 (“the '975 publication”). The latch actuator disclosed by the '975 publication lifts up the hood with fluid or air pressure. As a result, the size of the latch actuator is enlarged. Moreover, the fluid or gas leaks out of the latch actuator with time.
The Japanese Patent Publication No. JP 2007/296872 (“the '872 publication”) discloses an active hood system with an actuator for lifting up the hood of the vehicle as another example. The actuator in the '872 publication includes a multipart extendable cylinder, a rod, and a gas generator. In the actuator, since the hood is lifted up by the pressure of the gas, which is generated in the gas generator, it is not reusable and there are difficulties in its repair and security.
For yet a further example, there is a pedestrian protection apparatus described in the International Publication Patent No. WO 2003/095273 (“the '273 publication”). The pedestrian protection apparatus of the '273 publication is simple in structure because of the use of the elastic force of a plate spring. However, the pedestrian protection apparatus should unlock the plate spring, which is suppressed by a large amount of pressure. Due to this, the pedestrian protection apparatus requires an actuator strong enough to quickly generate a large amount of power.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.